Pyrazolo[1,5-a]-1,3,5-triazine C-nucleoside as deoxyadenosine analogue: synthesis, pairing, and resistance to hydrolysis.

The synthesis of a pyrazolo[1,5-a]-1,3,5-triazine C-nucleoside (dA(PT)), designed to form two hydrogen bonds with a complementary dT residue, is reported. Oligonucleotides including this dA nucleoside analogue possess base-pairing properties similar to those of the parent oligonucleotide. This dA nucleoside analogue is more resistant to acid-catalyzed hydrolysis than dA.